Common Dirty Carburetor Symptoms

Maintenance how-to's and guides for the induction system including the airbox, carburetors, fuel tank, fuel pump, petcock and hoses.
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There are three common circuits within the carburetor which have very small orifices and which clog easily from dirty fuel, stale fuel, or tank rust. These need to be absolutely clean in order for the bike to idle and run correctly. Verify these are clean by passing a wire through them and then shining a light.

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  • 1. Emulsion tube orifices - if clogged, these will affect fuel flow into the carburetor when the bike is at 1/8 throttle or greater.
    2. Pilot jet - the orifice in this jet is .172mm in diameter. It clogs easily. If this happens, your bike won't start or idle. Pass a wire through the jet and its air tubes and ensure both are clean.
    3. Enrichment orifice - this is even smaller than the pilot jet. I'd estimate .05 or .08mm in diameter. This one clogs very easily. If this happens, your "choke" won't work and the bike will be very difficult to start on all but the hottest days. Pass a single strand of 12 or 10-gauge wire through this opening to ensure its clear.
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